The invention pertains to a master for the duplication of sound recordings in the form of pits arranged in a spiral on a circular carrier disc and to a process for the production of the master itself by the use of a plate made of silicate glass with a pressing surface carrying the sound recording in the form of raised contours formed from a developed photoresist. A layer of primer holds the photoresist to the surface of the glass plate, a first layer of metal covers the pressing surface, and a protective layer of metal covers the first layer on the outside.
Layers of nickel or silver which have been sputtered onto the applied and developed photoresist layer or onto the exposed and developed positive resist surface, the nickel or silver layers being reinforced with thicker Ni layers deposited by electrolytic processes, are known.
A disadvantage of the known processes for the production of masters is attributable to the property of the photoresist layer to adhere at least partially to the master after the master has been separated from the layer of photoresist. This leads to serious problems in the following production of the carrier disks (CD's), because residues of the photoresist layer or of the primer could remain on the carrier disks which are pressed later on.